Influence of Regulated Metal Deposition and Gas Metal Arc Welding on ASTM A387-11-2 Steel Plates: As-deposited Inspection, Microstructure, and Mechanical Properties

In this work, 6-mm-thick ASTM A387-11-2 steel plates have been butt welded at optimized parametric settings of current (A) = 100 A, voltage (V) = 13 V, and gas flow rate (GFR) = 21 L/min. The as-welded plates have been visually inspected for any surface defects and were found to be defect-free. Further, the weldments were subjected to macroscopic metallography to explore the weld bead geometry. Macroscopic results reveal that the RMD process produces a higher depth of penetration (DOP) and lower heat-affected zone (HAZ) as compared to the GMAW process. Optical and scanning electron microscopy have also been done to examine the internal microstructure in the weldments. The result of microscopic analysis reveals the presence of pearlite and ferrite in the base metal. The process of grain refinement in the heat-affected zone and weld zone was also observed in the form of fine-grain particles which confirms the presence of martensite in the weld zone. In addition to this, the microhardness values for both weldments were measured and compared. The microhardness of GMA weldments was found to be too high in all the zones as compared to that of RMD weldments and hence gives the affirmation with the obtained microstructures in the welded samples.